This disclosure relates generally to an X-ray tube, and more particularly to an injection molded segmented target assembly for an X-ray tube that is designed for high-speed operation.
Modern medical imaging systems have increased in complexity and imaging capabilities. As computed tomography (CT) imaging systems increase gantry speed in order to image organs and other structures with increasing detail, X-ray tube requirements must increase as well. At these higher gantry speeds, parameters like peak power and anode target rotational speed must be optimized in order to meet the high demands of next generation X-ray tubes. An X-ray tube generally includes a cathode assembly and an anode assembly disposed within a vacuum vessel. The anode assembly includes an X-ray tube target assembly. The X-ray tube target assembly typically consists of a rectangular cross-section target disk that is machined at its periphery to include an angled surface creating an impact zone for an electron beam from the cathode assembly for X-ray generation. The target disk is commonly a rotating disk. With higher peak power requirements, higher rotational speeds and thermal loads on the target disk, the simple rectangular cross-section is no longer sufficient. The increased rotational speeds of the target disk may result in high stresses to the hub portion of the target disk that exceeds present design criteria. The hub portion is the center portion of the target disk that is coupled to a drive shaft. As target disk geometries become more complex, the typical manufacturing and machining processes, such as pressing, sintering and forging used today results in a highly inefficient process. The manufacturing and machining operations are more numerous and more complicated with the cost of parts increasing significantly.
The cathode assembly is positioned at some distance from the anode assembly creating a vacuum gap between the cathode assembly and the anode assembly, and a high voltage potential difference is maintained therebetween. The cathode assembly emits electrons in the form of an electron beam that are accelerated across the potential difference and impact the target disk at a focal spot of the impact zone at a high velocity. As the electrons impact the impact zone of the target disk, the kinetic energy of the electrons is converted to high-energy electromagnetic radiation, or X-rays. The X-rays are then transmitted through a window in the X-ray tube to an object such as the body of a patient and are intercepted by a detector that forms an image of the object's internal anatomy.
In any X-ray tube target assembly design it is likely that the target disk or portions thereof will suffer damage during prolonged usage. This is simply a result of the target disk being impacted by an electron beam to facilitate the generating of X-rays. When the wear or damage becomes too great, existing designs require complete replacement of the target disk. Disassembly and repair is not contemplated by existing designs and may be impractical based on design configurations and associated costs. Since such wear and damage may only occur on certain portions of the target disk, a design where only those portions of the target disk are replaced would be beneficial. In addition, where repair is still not cost effective, a design that allowed reuse of certain portions of the target disk would provide desirable cost benefits.
Therefore, it would be highly desirable to have an X-ray tube target assembly that allows for simplified replacement of worn or damaged portions of the target disk. It would also be highly beneficial to have an X-ray tube target assembly that was manufactured under new manufacturing processes and is capable of withstanding high peak power requirements, high rotational speeds and increased thermal requirements of modern anode assembly performance.